Linux: Use After Free
CVE-2026-53085 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 239cec25a22662dbd80f57d94b38178c8be95269, d0862de7c866c5bd7c32531f66738c21197af888, 43683bb280330f3d36f0f2a3932a4867b9603e9c as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.18% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 239cec25a22662dbd80f57d94b38178c8be95269 or d0862de7c866c5bd7c32531f66738c21197af888 or 43683bb280330f3d36f0f2a3932a4867b9603e9c or d8e27d2d22b6e2df3a0125b8c08e9aace38c954c, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.91 or 6.18.33 or 7.0.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 4ac4546821584736798aaa9e97da9f6eaf689ea3 up to, but not including, 239cec25a22662dbd80f57d94b38178c8be95269; 4ac4546821584736798aaa9e97da9f6eaf689ea3 up to, but not including, d0862de7c866c5bd7c32531f66738c21197af888; 4ac4546821584736798aaa9e97da9f6eaf689ea3 up to, but not including, 43683bb280330f3d36f0f2a3932a4867b9603e9c; 4ac4546821584736798aaa9e97da9f6eaf689ea3 up to, but not including, d8e27d2d22b6e2df3a0125b8c08e9aace38c954c; 6.7 | 239cec25a22662dbd80f57d94b38178c8be95269, d0862de7c866c5bd7c32531f66738c21197af888, 43683bb280330f3d36f0f2a3932a4867b9603e9c, d8e27d2d22b6e2df3a0125b8c08e9aace38c954c |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Linux | Linux Kernel | 6.7 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10 | 6.12.91, 6.18.33, 7.0.10 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 6.4 | Medium | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: bpf: fix mm lifecycle in open-coded task_vma iterator The open-coded task_vma iterator reads task->mm locklessly and acquires mmap_read_trylock() but never calls mmget(). If the task exits concurrently, the mm_struct can be freed as it is not SLAB_TYPESAFE_BY_RCU, resulting in a use-after-free. Safely read task->mm with a trylock on alloc_lock and acquire an mm reference. Drop the reference via bpf_iter_mmput_async() in _destroy() and error paths. bpf_iter_mmput_async() is a local wrapper around mmput_async() with a fallback to mmput() on !CONFIG_MMU. Reject irqs-disabled contexts (including NMI) up front. Operations used by _next() and _destroy() (mmap_read_unlock, bpf_iter_mmput_async) take spinlocks with IRQs disabled (pool->lock, pi_lock). Running from NMI or from a tracepoint that fires with those locks held could deadlock. A trylock on alloc_lock is used instead of the blocking task_lock() (get_task_mm) to avoid a deadlock when a softirq BPF program iterates a task that already holds its alloc_lock on the same CPU.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Third-party and government advisories
- access.redhat.com/security/cve/CVE-2026-53085Third Party Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2492404Third Party Advisory
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53085.jsonThird Party Advisory
Recent Use After Free vulnerabilities
- 7.5 High severity
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.6 Critical severity
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